Little is known of the role of parental occupational exposures or perinatal drug ingestion in the subsequent development of childhood acute lymphocytic leukemia. This study has two goals: a) development of a method for obtaining parental occupational and perinatal drug exposures, and b) testing this method on parents of children diagnosed as having acute lymphocytic leukemia, between 1972 and 1979 in the State of Washington. Cases have been identified in the three major hospitals treating children with cancer in the State. For each case a hospital control has been selected to attempt to control for any differences in recall between parents of ill and presumably well children. General population controls will be obtained by use of a random digit dialing method. To date, 80% of case parents have been interviewed. Occupational data include a detailed review of occupational history and review of each job-related exposure. A detailed review of perinatal drug ingestion is obtained.